The proposed work will continue the ongoing studies of glutathione metabolism in the ocular lens, and will concentrate upon the following areas: The control mechanisms of gamma-glutamylcysteine synthetase, the first of the enzymes to catalyze the two-step biosynthesis of glutathione, will be studied. Unraveling of the complicated mechanism of glutathione synthetase by use of enzyme kinetics, will be continued. A study of the effects of various cataractogenic agents upon the activity of these two enzymes will be continued. Purification of glutathione peroxidase is expected to be finished and many of the properties of the isolated enzyme will be studied. Studies of the effects, if any, of ultraviolet light, a cataractogenic agent, upon glutathione metabolism in the lens will be initiated. Additionally, assay of the activity of certain of the enzymes of glutathione metabolism in the human lens will be initiated.